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Old 07-26-2019, 08:23 AM
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blackshire blackshire is offline
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Join Date: Jan 2009
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Default SLS delayed again...

Hello All,

Scott Manley, a reliable space reporter, historian, and analyst, has said *here* www.youtube.com/watch?v=ba087WZHXZE (at the 3:50 point of the 6:19 video) that the SLS has been pushed back yet again—now to 2021. I’m not surprised, given that the NASA administrator pleaded for additional funding a few days ago, so that the vehicle could (hopefully) be ready in time to meet President Trump’s firm “boots back on the Moon within five years”—by 2024—schedule (Vice President Pence has repeatedly reminded NASA that if their hardware isn’t ready, privately-developed hardware will be used instead). Having a definite date focused NASA on the "Kennedy goal" with Apollo; both before and after Apollo, the lack of a firm "do-by date" for big projects such as that resulted in incremental progress toward an indefinite future implementation date. Also:

Since the SLS is a creature of politics (NASA was never very wild about building it, and even submitted its “just one launch every few years” schedule to, in part, discourage the Congress from supporting it—but the Shuttle-building legacy aerospace firms lobbied key Senators hard enough, hence the vehicle’s nickname, “Senate Launch System”), now is the time to pull the plug on the whole sordid mess (the upcoming BFR--or even multiple Falcon Heavy launches--could achieve the 2024 goal, including the Gateway station). With the recent deficit-ignoring two-year budget deal (in which the nation’s debt ceiling won’t be raised during that period—many Republicans, including the President, don’t like it for that reason), the President has the perfect excuse for ceasing to throw any more good money after bad with the SLS. The SLS’s planned CubeSat-size payloads—including the solar sail NEA Scout asteroid probe—could instead fly, and sooner, as “hitch-hiker" payloads on Falcon 9 and/or Falcon Heavy (or Electron, perhaps as primary payloads) flights, and:

To reduce the bitterness of that medicine, the development of the reusable and man-rated—but to be discarded, on SLS missions—RS-25 (the modified SSME [Space Shuttle Main Engine] used on the SLS core stage) and RL10C-3 (for the SLS second stage) could be continued, to simplify their construction (lower parts count, fewer welds, etc., by using 3D printing—this is already being done with the RL10) and improve their performance, as both rocket engines would have many uses in future reusable launch vehicles and space tugs. Both rocket engines could also be used (including simultaneously, in the same vehicle) to power smaller, air-launched orbital spaceplanes. For example:

Teledyne Brown Engineering’s Spaceplane (designed by Dan DeLong) was an unpiloted, 747-launched vehicle powered by one SSME and four RL10s (both engines could safely be ignited at 30,000 feet with their vacuum-optimized nozzles, with no flow separation problems), which had a shortened (21’ long), Shuttle Orbiter-size cargo bay, containing all of the standard Orbiter payload interfaces. It also had the capability, if its SSME failed to ignite (the RL10s effected separation, to protect the 747's tail fin from the SSME's exhaust plume; it was to ignite seconds after 747 separation), to autonomously fly to an abort airfield under the power of the RL10s, on a course designed to expend the excess propellants en route. Plus:

Numerous SSTO and TSTO (winged as well as ballistic) launch vehicles, manned and unmanned, and of various sizes and payload capabilities, could use both engines. These include vertical takeoff & landing vehicles such as MBB’s (of Germany) BETA and BETA II plug-nozzle vehicles. Their designs used ordinary bell-nozzle engines, thrusting through openings in the bottom combination heat shield/plug nozzle; at higher altitudes, the engines’ expanding exhaust plumes pushed against the bottom of the vehicle, increasing its thrust and therefore its performance. The RL10 would also make an excellent reusable space tug engine (in the 1970s NASA developed not only space tug designs, but [for manned planetary missions--Luke Strawalker posted the report here on YORF] also a Saturn S-IVC LOX/LH2 stage—with much better insulation to greatly reduce propellant boil-off—several of which would have been “stacked” in tandem to form an “orbital launch vehicle” to boost heavy manned interplanetary spaceships out of Earth orbit). With today’s better insulating materials technology, such LOX/LH2 space tugs--and propellant depots in orbit--would be feasible.
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